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S ECOR
<br /> • QUARTERLY STATUS AND REMEDIAL SUMMARY REPORT
<br /> First Quarter 2005
<br /> 76 Service Station #5886
<br /> 2701 West March Lane, Stockton, California
<br /> SITE SETTING
<br /> Union Oil Company of California (Unocal) purchased the land at 2701 West March Lane,
<br /> Stockton, California in 1967, at which time the property was vacant In 1982, Unocal
<br /> constructed a service station at the site and installed three 12,000-gallon underground
<br /> storage tanks (UST) to store gasoline and diesel fuels (Delta Environmental Consultants,
<br /> Inc [Delta], February 6, 1996)
<br /> PREVIOUS ASSESSMENTS
<br /> 1995 - Unocal removed three 12,000-gallon fuel USTs, product piping, and dispensers
<br /> Unocal replaced the fuel USTs with two 15,000-gallon and one 12,000-gallon UST The
<br /> UST replacement activities included disposal of approximately 1,200 cubic yards of soil
<br /> at Forward Landfill in Manteca, California and disposal of approximately 15,000 gallons
<br /> of groundwater at Unocal's Rodeo, California facility (Delta, February 6, 1996)
<br /> September 1995 - Unocal advanced 21 soil borings and collected soil and groundwater
<br /> samples from the borings utilizing a Geoprobe® sampling system (Delta, February 6,
<br /> i1996)
<br /> June 1996 - Unocal performed a water-supply well survey within a i/4-mile radius of the
<br /> site The survey identified 10 wells located within the survey area These wells are
<br /> located northeast to southeast of the site and are utilized as cathodic protection or
<br /> irrigation wells (PEG, June 24, 1996)
<br /> September 1996 - Unocal drilled four additional soil borings, and constructed
<br /> groundwater monitoring wells in three of these borings (Delta, December 5, 1996)
<br /> March 1997 to April 1997 - Tosco consultants submitted a Work Plan for Supplemental
<br /> Environmental Investigation (Environmental Resolutions, Inc [ERI], March 28, 1997) and
<br /> an Addendum to Work Plan (ERI, April 3, 1997)
<br /> April 1997 — Tosco performed a soil and groundwater investigation at the site in
<br /> accordance with the Work Plan for Supplemental Environmental Investigation (ERI,
<br /> March 28, 1997) and the Addendum to Work Plan (ERI, April 3, 1997) The investigation
<br /> included hand-auguring three soil borings adjacent to catch basins, drilling four soil
<br /> borings, and constructing dual-completion groundwater monitoring wells (MW4SID
<br /> through MW7S/D) at discrete depths in the borings (ERI, June 3, 1997)
<br /> July 1997 to August 1997 - Tosco submitted a Work Plan for Supplemental
<br /> Environmental Investigation (ERI, July 14, 1997) and an Addendum to Work Plan (ERI,
<br /> August 8, 1997)
<br /> July 1997 to December 1998 — Tosco performed the following tasks 1) conducted an
<br /> underground utility search (ERI, October 6, 1997), 2) performed quarterly groundwater
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